Action Points

Note that this large observational study utilizing food frequency questionnaires found a higher risk of obesity-associated cancers in normal-weight women who ate foods high in energy density.

This association was not seen in overweight or obese women, however.

A diet rich in energy dense foods may be tied to a higher risk of certain cancers among normal-weight, postmenopausal women, researchers reported.

Consumption of higher dietary energy density (DED) -- the ratio of calorie intake to food weight -- was associated with a 10% higher risk of developing obesity-related cancers (subhazard ratio Q5 versus Q1: 1.1, 95% CI 1.03-1.2, P=0.004, P=0.001 for trend), according to Cynthia A. Thomson, PhD, RD, of the University of Arizona Mel and Enid Zuckerman College of Public Health in Tucson, and colleagues.

Women who reported a diet high in DED foods also tended to have a higher BMI at 28.9 ± 6.0 (quintile 5) versus 26.3 ± 4.9 (quintile 1) and waist circumference at 89.3 ± 14.2 cm, or about 35 inches, (quintile 5) versus 82.4 ± 12.4 cm (quintile 1) versus a low DED diet, they wrote in the Journal of the Academy of Nutrition and Dietetics.

"It's always important to identify modifiable diet behaviors that hold potential to reduce disease risk -- in this case cancer risk," Thomson told MedPage Today in an email. "Dietary energy density is a way to think about the quality of the foods you select to eat and make decisions to improve those selections and potentially reduce your risk for cancer."

Thomson's group highlighted that up to 30% of cancers might be prevented with diet modification -- particularly among obesity-related cancers such as colorectal, ovarian, breast, endometrial, pancreatic, esophageal, gallbladder, and kidney cancers. However, the underlying mechanisms regarding the association between a high DED diet and heightened associated chronic disease risk require greater research.

They assessed 92,295 postmenopausal women, ages 50 to 79, who were participants in the multi-center Women's Health Initiative (WHI). Dietary patterns were self-reported with a food frequency questionnaire to determine DED quintile, stratified between 1 to 5 (highest). Baseline cancer screening was also self-reported. With death identified as a competing risk factor, the researchers utilized a competing-risk model to determine the relationship between DED and incident cancer cases, as well as onset of individual cancer type.

Although a higher DED was linked to heightened risk of any obesity-related cancers, no specific cancer type was reported to reach statistical significance after adjustment for confounding factors.

Although the highest quintile DED was associated with an elevated waist circumference and higher BMI, overweight and women with obesity were not found to have any significant associations between DED and associated cancer risk. Instead, only women of normal-weight at baseline reported any increased risk -- with such individuals in the 3rd, 4th, and 5th DED quintile reporting having an associated 10%, 18%, and 12% higher risk of any obesity-related cancer versus those in quintile 1 (subhazard ratio 1.2 for trend, P=0.006).

The authors expected to find that a better quality diet would be tied to a lowered cancer risk, Thomson explained. "It was very interesting to see this relationship was largely the result of dietary choices among women who were of normal weight," she added. "I think it's important to reinforce to women that having a healthy weight -- while important -- does not override the importance of healthy food choices."

However, the group added it was "novel and contrary to our hypothesis" that this relationship was exclusive to normal-weight women. "This finding suggests that weight management alone may not protect against obesity-related cancers should women favor a diet pattern indicative of high energy density," they wrote, adding that metabolic dysfunction may be an underlying mechanism to this relationship, exclusive of total body weight.

Thomson told MedPage Today that her group intends to assess the same dietary quality score of DED in relation to weight change after menopause.

Click here for the American Association of Clinical Endocrinologists and American College of Endocrinology comprehensive clinical practice guidelines for the medical care of patients with obesity.

The study was supported by the National Cancer Institute of the National Institutes of Health and the University of Arizona Collaboratory for Metabolic Disease Prevention and Treatment.

WHI is funded by the National Heart, Lung, and Blood Institute, the NIH, the U.S. Department of Health and Human Services.

Thomson and co-authors disclosed no relevant relationships with industry.

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